Cutting operations in which a workpiece is cut and shaped using a tool, such as, in particular, turning, drilling, and threading, may produce stringy swarf formed of lengthily joined pieces of swarf. The thus-produced stringy swarf may be wound around the workpiece and the tool, resulting in deteriorated processing accuracy, occurrence of a scratch on a machined surface, degradation of the tool, a halt of machining operation, or other failures. Further, once the stringy swarf has been wound around the tool and other components, because it is almost impossible to automatically remove the wound stringy swarf, machining operation should be temporarily interrupted in order to allow an operator to manually remove the stringy swarf. Such a removal task greatly decreases an operating rate of the machine tool.
Under the circumstances, techniques for preventing winding of the stringy swarf have conventionally been suggested. The suggested techniques include, for example, intermittently performing cutting operation to shorten a length of stringy swarf, and blowing the stringy swarf by means of a jet of a high-pressure coolant. However, the intermittent cutting operation raises other problems in that a lifespan of a tool blade is shortened and that the length of lead time is increased. On the other hand, in the case of using the jet of the high-pressure coolant, the jetted coolant may enter the inside of a telescopic cover and exert detrimental effects on a sliding part.